Automatic assembly machine

ABSTRACT

Screws fed from a hopper to an elongated delivery track by a feeding drum are picked up one-by-one from the track by a transfer device and are delivered to a chuck which surrounds a power rotated and power reciprocated screwdriver for driving the screws into a workpiece.

United States Patent Dixon [451 July 11, 1972 s41 AUTOMATIC ASSEMBLYMACHINE 56 Reference Cited |72| Inventor: Paul II. Dlxon. c/o DixonAutomatic Tool, UNITED STATES PATENTS Avenue' aelvidere' 3,583,4516/l97l Dixon ..29/240 x 3279.045 l0/I966 Dixon ..29/2|1 R 221 Filed:Dec. 9, 1970 Primary Examiner'fl|omas H. Eager [2| Appl. No.: 96,329Anomey-Wolfe. Hubbard, Leydig. Voit 8: Osann. Ltd.

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sum 10 0F 10 AUTOMATIC ASSEMBLY MACHINE BACKGROUND OF THE INVENTION Thisinvention relates to an automatic assembly machine for driving threadedfasteners into a workpiece and, more particularly, to a machine whichincludes a power rotated fastener driver adapted to be reciprocatedthrough downward and up ward strokes. Machines of this general type areshown in Dixon U. S. Pat. Nos. 2,989,996 and 3,279,045.

During the downward stroke of the driver of the machine, a fastener heldin a chuck is engaged by the driver and is threaded into the workpiece.Before the next downward stroke of the driver, a transfer mechanismpicks up another fastener from an elongated delivery track and positionsthe fastener adjacent the chuck, the fasteners being delivered to thetrack in randomly oriented positions by a power rotated feeding wheelwhich scoops the fasteners from a supply hopper and drops the fastenersonto the track. A rotatable clearing wheel is positioned above the trackand sweeps improperly oriented fasteners off of the track and back intothe hopper so that only properly oriented fasteners are allowed toproceed along the track to the transfer mechanism for delivery to thechuck.

SUMMARY OF THE INVENTION The general aim of the present invention is toprovide a new and improved machine of the above character which issimpler in construction than prior machines and which, at the same time,is more reliable and trouble-free in service use. In large, theforegoing ends are achieved through the provision of a machine whosevarious operating mechanisms are constructed in a novel manner so as tobe more independent of one another than has been the case heretofore sothat each mechanism may be adjusted and timed as necessary withoutsignificantly affecting the other mechanisms and requiring retiming ofthe overall machine.

A further object is to drive the feeding and clearing wheels in asimplified manner in timed relation with reciprocation of the driver andto uniquely effect rotation of the wheels at the most advantageous ratefor optimum feeding and clearing of the fasteners.

Another object of the invention is to provide the machine with a new andimproved fastener-holding chuck which positively telescopes downwardlyover and grips each fastener delivered by the transfer mechanism, thechuck coacting with the transfer mechanism at the end of each cycle andgripping the fastener prior to the next downward stroke of the driver sothat the transfer mechanism can be retracted well clear of the driverbefore the latter is advanced through its downward stroke.

A further aim is to reciprocate the driver and to drive the transfermechanism with separate actuators to reduce the complexity of themachine, outward movement of the transfer mechanism being governed byupward movement of the driver through the provision of a simplifiedmechanical interlock between the transfer mechanism and the driver.

The invention further resides in the novel and simplified constructionof the transfer mechanism to keep the mechanism from moving away fromthe delivery track until a fastener has been picked up and to keep themechanism for moving away from the chuck until the fastener has beenreleased.

Still another object of the invention is to provide the machine with anew and simplified finder device which coacts with a novelworkpiece-holding fixture to properly locate the driver relative to theworkpiece in quicker and easier manner than has been possibleheretofore.

These and other objects and advantages of the invention will becomeapparent from the following detailed description taken in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side elevationof a new and improved machine embodying the novel features of thepresent invention.

FIGS. 2, 3 and 4 are enlarged fragmentary cross-sections takensubstantially along the lines 2-2, 3-3 and 4-4, respectively, of FIG. 1.

FIG. 5 is a perspective view of the clearing wheel.

FIGS. 6 and 7 are enlarged fragmentary cross-sections takensubstantially along the lines 6-6 and 7-7, respectively, of FIG. 1.

FIGS. 8 to 11 are perspective views illustrating various parts of thetransfer mechanism and of the support therefor.

FIG. Ila is a diagrammatic view illustrating part of the transfermechanism.

FIGS. l2, l3 and 14 are enlarged fragmentary side eleva tional views ofpart of the machine and illustrating the successive steps of anoperating cycle.

FIG. 15 is an exploded perspective view of the chuck.

FIG. 16 is a perspective view of a mounting sleeve which telescopicallyreceives the chuck.

FIG. I7 is a diagram of a circuit for controlling operation of themachine.

FIG. 18 is a fragmentary side elevation of a modified machineincorporating the features of the invention.

FIG. I9 is an enlarged fragmentary cross-section taken substantiallyalong the line l9-I9 of FIG. 18.

FIG. 20 is a perspective view of still another machine embodying thefeatures of the invention, the machine being equipped with a finder forlocating the driver properly relative to the workpiece.

FIG. 21 is a fragmentary cross-section taken substantially along theline 2I21 of FIG. 20.

FIG. 22 is a fragmentary cross-section taken substantially along theline 2222 of FIG. 21.

FIG. 23 is a fragmentary plan view of part of the finder.

DETAILED DESCRIPTION As shown in the drawings for purposes ofillustration, the invention is embodied in an automatic assembly machine25 operable to drive threaded fasteners 26 (FIG. 1) into a workpiece 27held by a fixture 29. While the machine is capable of driving fastenersof various types, the fasteners have been illustrated herein as beingslotted-head screws which are adapted to be driven by a power rotatedand power reciprocated tool in the form of a screwdriver 30 (FIG. 12)having a blade-like tip 31.

The screwdriver 30 is supported on a carriage 33 (FIGS. 1 and 2) and isreciprocated upwardly and downwardly as the carriage is slid verticallyin opposite directions along an upright guide rod 34 by a double-actingpneumatic actuator 35, both the guide rod and the actuator being mountedon the outer portion of a generally upright, open-sided casting orsupport member 36 (FIGS. 1 and 3) anchored to a base 37 and forming themain support for the various elements of the machine 25. Pressurizationof the upper end of the actuator 35 from an air supply 39 (FIG. 17) toshift the screwdriver downwardly is effected when a spring-loaded mainvalve 40 is shifted by depressing a manually operable control button 41and, when the button is released, the lower end of the actuator ispressurized to retract the screwdriver upwardly. Adjustable restrictions43 associated with check valves 44 in the pneumatic control circuit ofthe actuator govern the escape of air out of the actuator in such amanner that the idle upstroke of the screwdriver occurs at aconsiderably faster rate than the downstroke so as to reduce the overallcycle time. The machine operates quite rapidly and is capable of drivingshort screws 26 of the type illustrated in a one or two second cycle.

To rotate the screwdriver 30, a rotary air motor 45 is supported on thecarriage 33 and is operably connected to the upper end of thescrewdriver. As shown in FIGS. 1 and I4, the air motor is locatedadjacent the upper end of an upright sleeve 46 formed on the outer endof the carriage and is threaded onto the upper end of a tubular adaptor47 fitted within the sleeve and held against rotation therein by meansof a radially extending set screw 49. A coupling disposed within andforming part of the adaptor and indicated generally in FIG. 14 by thereference numeral 50 connects the rotor of the air motor with the upperend of the screwdriver 30, the latter extending downwardly through theadaptor 47. The particular motor which has been illustrated ispressurized and begins rotating when the control button 41 is firstdepressed to admit air into the upper end of the actuator 45 to shiftthe screwdriver downwardly. Thus, the screwdriver rotates as it movesdownwardly to first engage the screw 26 and then drive the screw intothe workpiece 27. When the screw becomes tightened, the operator of themachine 25 releases the button 41 to stop the rotary motor and, at thesame time, to pressurize the lower end of the reciprocating actuator 35and effect retraction of the screwdriver. By employing a differentadaptor, the motor 45 may be replaced with a so-called pushto-start" airmotor of the type which begins rotating only after the screwdriverencounters downward resistance resulting from the screw engaging theworkpiece. Also, air motors of different types and made by variousmanufacturers may be employed with the machine simply by replacing theadapter 47 with one constructed for use with the particular motorselected.

Initially stored in a hopper 51 (FIGS. 1 and 3) at the inner end of thesupport 36, the screws 26 are first delivered from the hopper to anelongated track 53 and then proceed one-byone down the track fortransfer to the screwdriver 30. The track is inclined downwardly fromthe hopper toward the screwdriver and is formed by a pair of bars 54(FIGS. 4 and held rigidly spaced apart on the support 36 so as to definea straight slot 55 adapted to be filled with a row of screws locatedwith their heads up and hanging from the bars, the screws being fed downthe slot by gravity and being prevented from jumping out of the slot bya hold-down bar 56 overlying the slot. The lower end of the slot isclosed by a pair of spring fingers 57 which hold the lowermost screw inthe slot and which snap apart when outward pressure is applied to thelowermost screw thereby to permit removal of that screw from the trackand to enable the entire row to slide one step down the track.

To deliver the screws 26 from the hopper 5! to the track 53, a powerrotated feeding wheel in the form of an open-sided drum 59 (FIG. I) isjournaled to turn within the hopper by a shaft 60 connected to thesupport 36 and carries on its inner periphery a series of angularlyspaced scoops 61. As the drum 59 is rotated counterclockwise (FIG. I),the scoops move downwardly through the hopper and pick up batches ofscrews which spill from the scoops and onto the track as the scoops movealong the upper arc of their circular path. Many of the screws spilledfrom the scoops are guided into properly oriented positions in the slot55 by a trough 63 (FIG. 3) located at the upper end of the track. Thosescrews which are dropped crosswise across the track or which areotherwise im properly oriented to proceed down the slot 55 are kickedofi of the track and back into the hopper by a power rotated clearingwheel 64 located just above the track near the upper end thereof, theclearing wheel being fast on a shaft 65 which is journaled in an arm 66supported by the hold-down bar 56.

The clearing wheel 64 is rotated in a counterclockwise direction (FIG.I) and is uniquely constructed to kick the misoriented screws 26 off ofthe track 53 in a positive manner and to throw the screws laterallytoward the support 36 and against the closed side of the feeding drum59. For this purpose, angularly spaced ribs 67 (FIG. 5) are formedaround the outer periphery of the wheel and are shaped similar to theteeth of a spiral gear, the ribs being spiraled at a predetermined helixangle and being inclined across the axis of the wheel such that theleading sides of the ribs face generally toward the support 36 and thefeeding drum 59. Thus, the spiraled ribs pick up any misoriented screwson the track and.

as shown in FIG. 4, dirow the screws laterally against the closed sideof the feeding drum from where the screws may fall back into the hopper51. Because the screws are thrown laterally against the closed side ofthe feeding drum and toward the corresponding side of the hopper, thereis no need to provide protective shrouding completely around theopposite side and the rear of the hopper and thus free access to thehopper and drum is possible,

According to one aspect of the invention, a novel, simplified andcomparatively trouble-free drive arrangement is provided for rotatingthe feeding drum 59 and the clearing wheel 64 in timed relation withreciprocation of the screwdriver 30 and, in the case of the embodimentshown in FIGS. 1 to 17, for rotating the drum and the wheel directly inresponse to reciprocation of the screwdriver. Moreover, advantage istaken of the differential rates of the upstroke and the downstroke ofthe screwdriver to effect relatively slow rotation of the feeding drumon the comparatively slow downstroke and to effect rapid rotation of theclearing wheel on the faster upstroke.

In the present instance, the above-described drive arrangement includesa plate 69 (FIGS. 1 and 2) mounted to reciprocate upwardly anddownwardly with the carriage 33 and formed along its inner edge with atoothed rack 70 which meshes with a pinion 7!. The latter is journaledon a stub axle 73 projecting laterally from the support 36 and is keyedto a pulley 74 which also is journaled on the stub axle. An endless belt75 is trained around and tensioned between the pulley 74 and anadditional pulley 76 (FIG. 3) formed integrally with a rotatable memberin the form of a sleeve 77 which is coaxial with a second stub axle 79anchored rigidly to and projecting laterally from the support 36.Accordingly, the sleeve 77 is turned counterclockwise (FIG. I) at apredetermined rate by the belt 75 when the rack 70 is shifted downwardlyon the downstroke of the screwdriver 30 and is turned clockwise at amore rapid rate when the rack is shifted upwardly during retraction ofthe screwdriver.

The slow counterclockwise rotation of the sleeve 77 is utilized to turnthe feeding drum 59 while the faster clockwise rotation of the sleeve isutilized to turn the clearing wheel 64. To these ends, two identical butoppositely positioned oneway clutches 80 and 81 (FIG. 3) of conventionalconstruction are supported on the stub axle 79 at opposite ends of thesleeve with the input elements 83 of the clutches being coaxial with andprojecting into the sleeve and being coupled for rotation with thesleeve by means of set screws 84. Pulleys 85 and 86 are mounted to turnwith the output elements 87 of the clutches 80 and 81, respectively, thelatter serving to cause rotation of the pulley 85 and idling of thepulley 86 when the sleeve 77 is rotated counterclockwise (FIG. I) andthen to cause rotation of the pulley 86 and idling of the pulley 85 whenthe sleeve is rotated clockwise. A drive in the form of a flexibleendless belt 89 (FIGS. I and 3) is trained around the pulley 85 and thefeeding drum 59 to rotate the latter counterclockwise when the pulley 85is rotated. Counterclockwise rotation of the clearing wheel 64 inresponse to clockwise rotation of the pulley 86 is effected by a crossedendless belt 90 stretched between the pulley 86 and a pulley 91 fast ofthe shaft 65 which supports the clearing wheel.

From the foregoing, it will be apparent that downward movement of thecarriage 33 to shift the screwdriver 30 downwardly results in the sleeve77 and the pulley 85 being turned counterclockwise (FIG. I) to effectturning of the feeding drum 59 in a corresponding direction and at acomparatively slow rate to advance a batch of screws 26 toward aposition above the track 53. During turning of the feeding drum, theclearing wheel 64 remains stationary and does not interfere with thedelivery of the screws onto the track because the one-way clutch 81enables the sleeve 77 to freewheel with respect to the pulley 86. Whenthe carriage is shifted upwardly to rapidly retract the screwdriver, thesleeve 77 and the pulley 86 are turned clockwise and, through thecrossed belt 90, effect counterclockwise turning of the clearing wheel64 at a very fast rate. The clearing wheel thus sweeps off of the track53 any misoriented screws previously delivered onto the track duringrotation of the feeding drum. As the clearing wheel rotates, the feedingdrum simply idles because of the one-way clutch 80. Accordingly, thedrum 59 and the wheel 64 are rotated at the proper times, at optimumrates, and in the correct direction by virtue of the relatively simpledrive arrangement provided by the rack 70 and pinion 71 along with theclutches 80 and 81 and the belts 89 and 90.

Each screw 26 at the lower end of the track 53 is picked up and removedfrom the latter by a transfer mechanism 93 and is shifted outwardly to adelivery station or position (see FIG. 14) beneath the screwdriver 30while the screwdriver is in its upwardly retracted position. When thescrew reaches the delivery position, it is gripped by a chuck 94 locatedadjacent the lower end of the screwdriver and, after the screw has beengripped, the transfer mechanism is shifted reversely or inwardly to aloading station or position (FIGS. 1, l0 and 12) to pick up anotherscrew from the track 53.

In accordance with another aspect of the invention, the transfermechanism 93 is constructed in a novel manner so as to be capable ofmoving outwardly from its loading position to its delivery position onlyafter first being conditioned to pick up a screw 26 from the track 53.Moreover, inward movement of the transfer mechanism back to the loadingposition is prevented until the transfer mechanism actually releases thescrew to the chuck 94. In this way, the timing of the movements of thetransfer mechanism is simplified as will become more apparentsubsequently and, in addition, there is no danger of the delivered screwbeing returned inwardly with the transfer mechanism and being yanked outof the chuck.

More particularly, the transfer mechanism 93 comprises a slide 95 (FIG.11) carrying a pair of jaws 96 for gripping the screws 26 and guided onthe support 36 for in and out movement along a generally arcuate path tomove the jaws between the loading and delivery positions shown in fulland phantom in FIG. 12. As shown in FIGS. 7, 8 and 11, the slide 95 isfitted between and guided by a pair of plates 97 held in spaced apartrelation by a center block 99 and fastened to the outer lower portion ofthe support 36 by screws 100 which also hole the plates and the blockassembled to one another. The slide 95 comprises a pair of side-by-sideblocks 101 (FIGS. 7 and 9) disposed between the plates 97 and eachformed on its outboard side with an arcuate rib 103 (FIG. 9) which isfitted slidably into and guided by a correspondingly shaped groove 104(FIG. 8) cut in the inner side of the adjacent plate. The two slideblocks are held against relative edgewise shifting by a pair of pins 105and 106 (FIG. 9) which extend slidably through sets of holes 107 and 108formed in the slide blocks, the sliding fit of the pins permitting theblocks to move broadwise away from one another. A coiled compressionspring 109 is telescoped into recesses 1 formed in the inner sides ofthe blocks and urges the blocks away from one another and into lightpressing engagement with the guide plates 97.

The jaws 96 are located near the outer lower ends of the slide blocks101 and are formed with opposed recesses 111 (FIG. 11) within which theshanks of the screws 26 are received as shown in FIG. 10. Each jaw iscarried on the lower end of a generally upright leg 113 (FIG. 11) whoseupper end is integral with a U-shaped yoke 114. Connector pins 115extending through the slide blocks 101 are attached pivotally to theyokes 114 to mount the jaws 96 for swinging between closed and openpositions shown in FIGS. 10 and 11, respectively, about axes extendingtransversely of the direction of sliding of the blocks.

At the beginning of each operating cycle, the slide blocks 101 aredisposed in upwardly retracted positions within the guide plates 97 tolocate the jaws 96 in their loading positions adjacent the lower end ofthe track 53 (see FIG. 12). After the jaws are swung closed to pick upand grip the lowermost screw 26 in the track, the slide blocks are sliddownwardly and outwardly to shift the jaws and the gripped screw to thedelivery position beneath the chuck 94 as shown in FIG. 14. The jawsthen are opened to release the screw and thereafter the slide blocks areshifted upwardly and inwardly to return the jaws to their loadingpositions.

To open and close the jaws 96 and move the latter between the loadingand delivery positions, an air cylinder 116 (FIGS. 1 and 14) is mountedon the side of the support 36 and includes a reciprocable plunger 117whose free end is connected pivotally to an arm 1 19 formed integrallywith and projecting radially from a sleeve 120 (FIG. 6) which isjournaled on a stub axle 121 projecting horizontally from the support.The free end of a bifurcated arm 123 (FIG. 14) projecting from thesleeve 120 is clamped by a screw 124 to the midpoint of a cylindricalrod 125 (FIGS. 7 and 11) which spans the upper ends of a pair ofgenerally upright links 126. The upper ends of the links 126 areconnected pivotally to the rod 125 while the lower end of each link isconnected pivotally to the yoke 114 of the adjacent jaw 96 by means of aspherical bearing 127, the latter being supported on a screw 129extending through the link and threaded into the yoke adjacent the upperend of the leg 113. The lower ends of the links 126 are offset laterallyfrom the connector pins 115 and thus, when the links are lowered andraised, the jaws pivot inwardly and outwardly about the pins and areswung between their closed and open positions.

As mentioned above, the jaws 96 are located in their loading positions(FIG. 12) and are open at the beginning of each operating cycle andremain so positioned during driving of the screw 26. When the screw hasbeen driven and the operator releases the push button 41 to pressurizethe lower end of the actuator 35 and retract the screwdriver 30, thehead end of the cylinder 116 is simultaneously pressurized to extend theplunger 117 outwardly. By way of the arm 119, the plunger 117 rocks thesleeve 120 and the arm 123 counterclockwise (FIG. 12) to force the links126 downwardly.

Initial downward movement of the links 126 causes the jaws 96 to beginswinging toward one another about the pins 115. At this time, however,the links 126 do not exert any substantial downward force on the slideblocks 101 because the downward motion of the links is taken up in theswinging of the jaws 96 about the pins 115. Also, the coil spring 109urging the blocks into pressing engagement with the guide plates 97creates a frictional resistance retarding downward movement of theblocks. Accordingly, as the links 126 initially move downwardly, theslide blocks 101 remain in their upper positions within the guide plates97 and keep the jaws 96 located in their loading positions adjacent thelower end of the track 53 while the jaws are swung closed.

As an incident to closing upon and engaging the lower screw 26 in thetrack 53, the jaws 96, by virtue of such engagement, are stopped fromswinging further about the pins 115. Thus, continued downward movementof the links 126 is transmitted to the slide blocks 101 through the pins115 and overcomes the friction created by the spring 109 so as to forcethe blocks to move downwardly within the guide plates 97 to move thejaws and the gripped screw downwardly and outwardly from the track tothe delivery position beneath the chuck 94 of the screwdriver 30.Accordingly, it will be seen that downward movement of the jaws cannotoccur until the jaws actually close on the screw and stop swinging aboutthe pins 115 and thus there is little danger of the jaws being movedaway from the track while still open.

Downward and outward movement of the jaws 96 occurs just after thescrewdriver 30 and the chuck 94 have been retracted upwardly out of thepath of the jaws. Movement of the jaws is stopped when a set screw 130carried by one of the slide blocks 101 engages a fixed pin 131 (see FIG.14) spanning the guide plates 97. At the same time the set screw engagesthe pin or just very shortly thereafter, a spring-loaded limit controlvalve 133 (FIGS. 14 and 17) mounted on the support 36 is shifted toinitiate the retraction of the plunger 117 of the cylinder 116. To shifithe valve 133, an adjustable set screw 134 (FIG. 14) is attached to thefree end of another am 135 carried by the sleeve 120 and projectinggenerally oppositely from the arm 123. When the arm 135 is rockedcounterclockwise through a predetermined distance during downwardmovement of the slide blocks 101, the set screw 134 engages one end of ashort lever 136 mounted pivotally on the support 36 and the projectingthrough an opening 137 therein (see FIG. 6). The lever thus engages anddepresses the plunger 138 of the valve 133 to shift the latter and causeretraction of the plunger 117 of the cylinder 116.

As the plunger 117 retracts, the arm 123 is rocked clockwise to raisethe links 126 upwardly. With initial upward movement of the links, thejaws 96 are pivoted on the pins 115 and are swung to open positions torelease the screw 26, the latter previously having been gripped by thechuck 94 in a manner to be described subsequently. Because the jawspivot on the pins, the initial upward movement of the links 126 isineffective to produce upward movement of the slide blocks 101 and thusthe jaws remain in the delivery position shown in FIG. 14 and do notshift upwardly while being opened. As the jaws reach their fully openpositions. bars 139 (FIG. 11) integral with upper ends of the yokes 114swing into engagement with the ends of the pin 106 and prevent furtherswinging of the jaws about the pins 115. Thus, continued upward movementof the links 126 is transmitted to the slide blocks through the pins 115so that the blocks are moved upwardly and inwardly to return the jaws totheir loading positions adjacent the lower end of the track 53.Accordingly, it will be apparent that the jaws cannot shift upwardlybefore the screw 26 is released and thus there is no danger that thejaws will jerk the screw out of the chuck 94. Also, because inward andoutward movement of the slide blocks 101 cannot occur until the jaws areopened or closed, the jaws are moved inwardly and outwardly and swungopen and closed in automatic timed relation and no critical adjustmentsare necessary to keep the various movements correlated.

Upward movement of the jaws 96 is terminated when downwardly projectinglugs 140 (FIGS. 9 and 12) on the lower sides of the slide blocks 101engage and stop against the pin 13] spanning the guide plates 97. Sincethe track 53 is fixed, the jaws always return upwardly and inwardly tothe same position. Provision is made, however, to adjust the extent towhich the jaws move downwardly and outwardly to their delivery positionsso as to enable exact positioning of the screw 26 directly beneath thechuck 94. Thus, by adjusting the set screws 130 and 134, the downwardand outward stroke of the jaws can be lengthened or shortened so thatthe jaws will stop precisely when the axis of the screw intersects avertical plane containing the axis of the chuck and extending laterallyof the direction of movement of the screw. Also, the jaws may beadjusted laterally relative to such plane to enable the screw 26 to becentered laterally with respect to the chuck. For this purpose, theupper end of each of the links 126 is supported on a spherical bearing141 (FIG. 11) and is connected to the rod 125 by a screw 143 extendingthrough the bearing and threaded into the rod. The axis b (FIG. 11a) ofone of the screws 143 is offset or eccentric in one direction relativeto the axis c of the rod 125 while the axis d of the other screw isoffset from the axis of the rod in the diametrically opposite direction.Thus, by loosening the clamping screw 124 and turning the rod 125relative to the arm 123, one of the links 126 may be slightly loweredwhile the other link is raised through a corresponding distance to causeboth jaws 96 to shift laterally in the same direction. In this way, thelateral position of the jaws relative to the chuck 94 may be adjustedinitially to center the jaws precisely with respect to the axis of thechuck and then the clamping screw 124 may be tightened to maintain thejaws in the thusly adjusted position.

By means of adjustable restrictions 144 (FIG. 17) associated with checkvalves 145 in the control circuit of the cylinder 116, the excape of airout ofthe cylinder is controlled in such a manner that the cylindershifts the jaws 96 outwardly at a comparatively slow rate to maintainbetter control of the gripped screw 26 and then returns the jawsinwardly at a faster rate to reduce the cycle time. Also, therestriction 144 controlling the escape of air from the plunger end ofthe cylinder is adjusted such that the cylinder nonnally moves the jawsoutwardly toward their delivery positions at such a rate that the jawsreach their delivery positions just after the actuator 35 has retractedthe screwdriver 30 and the chuck 94 upwardly out of the path of thejaws.

In another of its aspects, the invention contemplates the provision ofnovel mechanical means for protecting against any misadjustment in therate of escape of air from the actuator 35 and the cylinder 116 and forinsuring that, even if such misadjustrnent occurs, the cylinder will bepositively prevented from shifting the jaws 96 downwardly and outwardlyto their delivery positions until after the actuator 35 has retractedthe screwdriver 30 and the chuck 94 upwardly out of the path of thejaws. Herein, these means comprise still another arm 146 (FIG. 14)fonned integrally with and projecting radially from the sleeve 120 andcarrying a roller follower 147 on its free end. The follower ispositioned to engage and ride along a downwardly and outwardly inclinedcam surface 149 formed on the lower end of the plate 69 mounted on thecarriage 33.

When the screwdriver 30 is disposed in its downward, work ing position,the follower 147 is spaced inwardly from the plate 69 as shown inphantom in FIG. 14. Then, as the actua tor 35 is pressurized to retractthe screwdriver upwardly and the cylinder 116 is pressurizedsimultaneously to shift the jaws 96 outwardly, the follower 147 isrocked counterclockwise. If the cylinder 116 is moving the jawsoutwardly too rapidly, the follower engages the plate 69 and, as aresult of such engagement, prevents the jaws from being moved outwardlyby the force exerted by the cylinder. Then, as the screwdriver and theplate 69 retract upwardly, the follower 147 moves beneath and ridesalong the cam surface 149 and allows the jaws 96 to move graduallyoutwardly. The cam surface is shaped and located to coact with thefollower in such a manner as to prevent the jaws from moving outwardlyinto the path of the screwdriver and the chuck until the latter havebeen retracted upwardly out of the path of the jaws and thus, eventhough the actuator 35 and the cylinder 116 are pressurized at the sametime and even though the restrictions 43 and 144 may be out ofadjustment, there is no danger of the jaws shifting outwardly andcolliding with the chuck and the screwdriver. Accordingly, the follower147 and the cam surface 149 serve as a mechanical interlock to insurepositive control of the movement of the jaws in timed relation with themovement of the screwdriver.

According to another important aspect of the invention, the chuck 94 isconstructed in a novel manner to telescope downwardly over and grip eachscrew 26 delivered by the jaws 96 before any downward movement of thescrewdriver 30 and the carriage 33 takes place and before the actuator35 is pressurized to initiate such downward movement. To these ends, thechuck is mounted to move downwardly relative to the screwdriver and topick up the screw from the jaws when the screwdriver reaches itsupwardly retracted position near the end of each cycle. With the screwheld by the chuck, the jaws can then be returned inwardly to theirloading positions and out of the path of the screwdriver well before thelatter is started downwardly during the next cycle and thus not only isthe timing of the various operations less critical but also the view ofthe machine operator is not obstructed by the jaws as the screwdrivermoves downwardly and drives the screw.

More particularly, the chuck 94 is a tubular unit or sleeve formed bythree upright finger sections 150 of generally arcuate cross-section andarranged in edge-to-edge relation as shown in FIG. 15. At their upperends, the fingers 150 are telescoped into a sleeve-like collar 151 andare cantilevered hingedly to the collar by means of small pins 153projecting through the fingers and extending radially into the collar.Located between each pair of fingers is a bowed spring 154 (one visiblein FIG. 15) whose ends are fitted into recesses 155 in the edge of onefinger and whose bowed portion bears against the edge of the adjacentfinger. The springs urge the fingers away from one another to spreadpositions (FIG. 14) in which the free ends of the fingers are separatedsufficiently far to telescope easily over the head of the screw 26. Whenpushed toward one another, the free ends of the fingers close upon andgrip the screw (see FIG. 12).

As shown in FIG. 14, the collar 151 with the attached fingers 150 istelescoped slidably over the screwdriver 30 and into a sleeve 156 which,in turn, is fitted into the lower end of the sleeve 46 beneath theadaptor 47, the sleeves 46 and 156 being anchored together by a pin 157.A coil spring 159 is compressed between a portion of the adaptor 47 anda bush ing I60 fitted into the upper end of the collar 151 and urges thefingers I50 downwardly in the sleeve 156 to extended or loweredpositions as shown in FIG. 12. Prior to picking up the screw 26 from thejaws 96, however, the fingers 150 are held in upwardly retracted raisedpositions in the sleeve 156 (see FIG. 14). When the fingers are in theirraised positions in the sleeve 156, the bowed springs 154 force thefingers apart to enable the fingers to subsequently telescope downwardlyover the screw. As the fingers are shifted to their advanced loweredpositions by the coil spring 159 and telescope over the screw,downwardly tapered frusto-conical cam surfaces I61 (FIG. 15) formedintermediate the ends of the fingers slide downwardly across a similarlytapered cam surface 163 formed within the lower end of the sleeve 156.As a result of the cam surfaces 161 sliding across the cam surface 163,the fingers are forced together against the bias exerted by the bowedsprings 154 and close upon and grip the screw held by the jaws 96.

To hold the fingers 150 in their raised positions (FIG. 14) in thesleeve 156 against the bias exerted by the coil spring 159, a latch 164(FIG. 16) is carried on the outer side of the sleeve. In this instance,the latch is pivoted on a pin 16S fastened to the outer side of thesleeve 156 and includes an upwardly facing shoulder 166 (FIG. 13)projecting through an opening 167 in the sleeve and adapted to engagethe lower edge 168 of the collar 151 when the latch is in its latchedposition shown in FIG. 13 and in phantom in FIG. 14. The latch is urgedcounterclockwise toward its latched position by a U-shaped spring 169engaging the upper end portion of the latch and bearing against the pin165 and the outer side of the sleeve 156.

To explain the operation of the chuck 94 and to summarize the operationof the overall machine 25, let it be assumed that the screwdriver 30initially is disposed in its upwardly retracted position (as is the caseat the beginning of each cycle) and that the fingers 150 are holding ascrew 26 beneath the screwdriver (see FIG. 12). At this time, the jaws96 are at rest in their loading positions adjacent the track 53 as shownin full in FIG. 12, and the latch 164 for the chuck 94 is released withthe shoulder 166 thereof disposed above the lower edge 168 of the collar151 and in engagement with the side of the collar. Thus, the coil spring159 forces the fingers 150 to their lowered or advanced positionsrelative to the sleeve 156 and keeps the screw 26 positioned just ashort distance below the tip 31 of the screwdriver 30. The coil springalso forces the cam surfaces 161 on the fingers into engagement with thecam surface I63 on the sleeve 156 to keep the fingers closed in grippingengagement with the screw.

When the operator depresses the control button 41, the rotary air motor45 is energized and the upper end of the actuator 35 is pressurizedthereby to shift the screwdriver 30, the adaptor 47, and the sleeves 46and 156 downwardly in unison. At this time, the coil spring 159 acts asa rigid link between the adaptor 47 and the chuck 94 and forces thechuck and the gripped screw 26 to move downwardly in unison with thescrewdriver. During the downward movement of the screwdriver, thefeeding drum 59 is turned slowly to advance the scoops 61counterclockwise and to spill a batch of screws onto the track 53.

As the downwardly advancing screw 26 initially engages the workpiece 27,further downward movement of the chuck 94 is stopped. The coil spring159 compresses, however, and allows the screwdriver 30 and the sleeve156 to continue to move downwardly relative to the chuck. The rotatingscrewdriver thus moves downwardly into engagement with the head of thescrew and begins threading the screw into the workpiece (see FIG. 13).At the same time, the cam surface 163 on the sleeve 156 moves downwardlyaway from the cam surfaces 161 on the fingers to enable the bowedsprings 154 to spread the fingers apart suificiently far to release thescrew. Also, as shown in FIG. 13, the shoulder 166 on the latch 164moves downwardly alongside the collar I51 and then snaps inwardlybeneath the lower edge 168 of the collar as a result of the collar beingstopped while the sleeve 156 and the latch 164 carried thereon continueto move downwardly. Thus, as the screw is driven into the workpiece, thefingers 150 are held in their upper retracted positions within thesleeve 156 by the latch 164 and are spread apart as a result of the camsurfaces 161 being held upwardly away from the cam surface 163.

Afier the screw 26 has been driven, the operator releases the controlbutton 41 to pressurize the lower end of the actuator 35 and therebycause the screwdriver 30, the chuck 94 and the sleeves 46 and 156 tomove upwardly in unison at rapid rate, the fingers 150 of the chuckbeing held in their upper positions as they move upwardly. During suchupward movement, the clearing wheel 64 is rotated rapidly to sweep anyimproperly oriented screws 26 off of the track 53. In addition, when theactuator 35 is pressurized, the cylinder 116 also is pressurized andcauses the jaws 96 to pick up a screw from the track and to begin movingdownwardly and outwardly toward their delivery positions.

The jaws 96 approach their delivery positions just after the screwdriver30 and the chuck 94 have been retracted upwardly out of the path of thejaws and reach the upper end of the upstroke (see FIG. I4). As the jawsreach their delivery positions, an adjustable set screw 171 (FIGS. 9 andI4) carried on the outer end of one of the slide blocks 101 engages adownwardly projecting tail 173 on the latch 164 and pivots the latchclockwise from the position shown in phantom in FIG, l4 to the positionshown in full. As a result, the shoulder 166 on the latch is swungoutwardly from beneath the lower edge I68 of the collar 151 to enablethe collar and the attached fingers 150 to slide downwardly to theirlowered positions by virtue of the force exerted by the coil spring 159.The fingers thus telescope downwardly over the head of the screw 26 heldin the jaws 96 and, as the cam surfaces 161 slide downwardly over thecam surface 163, the fingers are forced together and close upon and gripthe screw (see FIG. 12) At this time, the set screw 134 on the arm 135hits the lever 137 and depresses the plunger 138 of the limit controlvalve 133 to cause the plunger 117 of the cylinder 116 to retractv Thejaws 96 thus are first opened up to release the screw 26 held in thechuck 94 and, after the screw has been released, the jaws are retractedinwardly to their loading positions adjacent the track 53 and well outof the downward path of the screwdriver 30. Accordingly, when anothercycle is initiated, the operator will have an unobstructed view as thescrewdriver moves downwardly and drives the screw previously loaded intothe chuck at the end of the preceding cycle. Also, with the jaws alwaysretracted prior to the screwdriver starting downwardly, sufficientvertical space is available to enable the incorporation of a vacuum ormagnetic chuck into the machine 25 if it is desirable to use a chuckother than the mechanical chuck 94.

The pneumatic circuit for controlling the foregoing operations will bedescribed briefly and is shown in FIG. 17 at the start of a cycle. Whenthe button 41 is depressed to shift the main control valve 40 from theposition shown, air is admitted through the valve 40 and to the pilotactuator 174 of a springloaded relay valve 175 thereby to shift thevalve Air then is directed through the relay valve 175 from the airsupply 39 and fiows into the upper end of the actuator 35 to start thescrewdriver 30 through its downstroke. At the same time, air flowsthrough the relay valve 175 to the pilot actuator 176 of a spring-loadedvalve 177 for controlling the rotary motor 45. The valve 177 thus isshifted and directs air from the supply 39 to the rotary motor toinitiate rotation of the screwdriver. For purposes to be describedsubsequently, air passing flirough the valve 175 during the downstrokeof the screwdriver flows into one pilot actuator 179 of a relay valve180 to shift the latter from the position shown and also flows into ashuttle valve 181 to move the ball 183 thereof from right to left.

After the screw 26 has been driven and the operator releases the button41 to return the main valve 40 to the position shown, the spring-loadedrelay valve 175 returns to its original position thus allowing thespring-loaded motor control valve 177 to return and cut off the flow ofair to the rotary motor 45. In addition, air is admitted through therelay valve 175 from the air supply 39 and flows into the lower end ofthe actuator 35 to begin retracting the screwdriver 30. At the sametime, air flows from the valve 175, through the previously shifted relayvalve 180, and into the head end of the cylinder 116 to begin shiftingthe transfer mechanism 93 outwardly to its delivery position.

When the transfer mechanism reaches its delivery position, the arm 135causes depression of the plunger 138 of the limit control valve 133 toshift the latter from the position shown. At this time, a momentarypulse of air passes from the supply 39, through the limit control valve133 and into the other pilot actuator 184 of the relay valve 180 therebyto return the latter to its original position. Air then flows from thesupply 39, through the relay valves 175 and 180 and into the shuttlevalve 181 to return the ball 183 thereof from left to right and to allowair to flow from the shuttle valve into the plunger end of the cylinder116 to retract the transfer mechanism 93 inwardly to its loadingposition, the arm 135 moving away from the spring-loaded plunger 138 ofthe limit control valve 133 to allow the latter to shift back to itsoriginal position. The transfer mechanism 93 stops upon returninginwardly to its loading position and, until another cycle is begun, isheld in such position by virtue of the air supply 39 communicating withthe plunger end of the cylinder 116 through the relay valves 175 and 180and the shuttle valve 181. Also, the transfer mechanism 93 is held inits loading position during the downstroke of the screwdriver 30because, as described above, the ball 183 of the shuttle valve 181 isshifted from right to left when the relay valve 175 is shifted to admitair into the lower end of the actuator. With the ball disposed in itsleftward position, air passes from the supply 39, through the relayvalve 175 and the shuttle valve 181, and into the plunger end of thecylinder 116 to hold the transfer mechanism 93 retracted as thescrewdriver 30 moves downwardly.

if for some reason the screw 26 picked up in the jaws 96 of transfermechanism 93 should happen to jam and prevent the transfer mechanismfrom moving fully outwardly to its delivery position and actuating thelimit control valve 133, the machine operator may manually pivot thelever 136, by engaging the end of the lever projecting through theopening 137 in the support 36, thereby to depress the plunger 138 andeffect opening of the jaws 96, release of the jammed screw and subsequent retraction of the transfer mechanism. The machine then may berun through an idle cycle to load another screw into the chuck 94.

It will be apparent from the foregoing that the present invention bringsto the art a new and improved automatic assembly machine 25 whosevarious operating mechanisms are comparatively simple in construction.While the operating mechanisms coact with one another and cause thedifferent operations to occur in proper sequence, each mechanism, forthe most pan, can be adjusted independently of every other mechanism andwithout afiecting the timing of such other mechanism. For example, letit be assumed that the machine is to be used to drive screws which aresomewhat longer than those illustrated. in such an instance, thescrewdriver reciprocates through a longer stroke and stops at the bottomof its downstroke at a position somewhat lower than that shown inphantom in FIG. 1 when shorter screws are being driven, the screwdriver,however, always starting from and returning to the same upper retractedposition shown in full in FIG. 1 regardless of the length of the screws.Even though the length of the stroke is changed, only the operation ofthe feed ing drum 59 and the clearing wheel 64 is affected directly.That is, the drum and die wheel will rotate through greater angulardistances as a result of the increased stroke but, in most cases, theadded rotation imparted to the drum and the wheel is insignificant.Because the jaws 96 of the transfer mechanism 93 are shifted by thecylinder 116 and not by the same actuator 35 used for reciprocating thescrewdriver, neither the length of the inward and outward stroke of thejaws nor the extent of the opening and closing movement of the jaws areeffected when the length of the stroke of the screwdriver is changed.When driving longer screws, it may be desirable for smoothness ofoperation to adjust the rate of actuation of the cylinder 116 so as toslow the rate at which the jaws 96 are advanced outwardly duringretraction of the screwdriver through its longer upstroke. Thisadjustment is not absolutely necessary, however, and is not criticalsince the follower 147 and the cam surface 149 insure that the jawscannot collide with the screwdriver 30 and the chuck 94 even though thelatter are shifted through a comparatively long upstroke.

Any adjustments necessary to the transfer mechanism 93 can be madequickly and easily. Thus, by adjusting the screws 130 and 134, thelength of the inward and outward stroke of the jaws 96 can be adjustedthereby to enable changing of the outer limit of the outer stroke sothat the jaws can be centered precisely beneath the chuck 94. If thestroke of the jaws is changed, the set screw 171 can be adjustedinwardly or outwardly as necessary to insure that the latch 164 will betripped at the proper time as the jaws approach the end of their outwardstroke. Accordingly, it is a comparatively simple matter to makeadjustments to the transfer mechanism and such adjustments do not affectthe timing or the length of stroke of the screwdriver.

DESCRIPTION OF ALTERNATE EMBODIMENTS A modified machine 25 is shown inFIGS. 18 and 19 in which parts corresponding to those of the firstembodiment are indicated by the same reference numerals. In thisinstance, the feeding drum 59 and the clearing wheel 64 are driven in aunique manner which insures that the drum and the wheel will be rotatedthrough precisely the same angular distance during each operating cycleregardless of the length of the stroke of the screwdriver 30. This isachieved by actuating the drum and the wheel in response to operation ofthe cylinder 116 instead of in response to reciprocation of thescrewdriver.

As shown in FIG. 18, a link 190 is pivotally connected at one end to theupper end of the arm 146 and thus is rocked inwardly and outwardly whenthe arm is rocked by the cylinder 116 as an incident to shifting thetransfer mechanism 93 inwardly and outwardly. The other end of the link190 is connected pivotally at 191 to an car 193 formed integrally withand projecting radially from a gear segment 194 which is mounted topivot on the support 36 at 195. The teeth of the gear segment 194 meshwith a gear 196 formed integrally with and encircling the sleeve 77intermediate the ends thereof.

Accordingly, when the arm 146 is rocked counterclockwise as the transfermechanism 93 is shifted outwardly, the link 190 is pulled outwardly andturns the gear segment 194 clockwise thereby resulting incounterclockwise turning of the gear 196 and the sleeve 77. Through theclutch and the belt 89, the sleeve 77 turns the feeding drum 59counterclockwise and at a relatively slow rate since the outward strokeof the transfer mechanism 93 is comparatively slow. When the transfermechanism is retracted inwardly at a more rapid rate, the arm 146 isrocked clockwise to push the link 190 inwardly and effect clockwiseturning of the sleeve 77. Thus, the clearing wheel 64 is turnedcounterclockwise by way of the clutch 81 and the crossed belt and isturned rapidly as a result of the arm 146 being moved at a fast rate asthe transfer mechanism is retracted.

From the foregoing, it will be seen that the angular distances throughwhich the feeding drum 59 and the clearing wheel 64 are rotated remainconstant regardless of the length of the stroke of the screwdriver 30and since, the length of the stroke of the transfer mechanism 93 isadjusted only infrequently and then by only nominal amounts, the drumand the wheel are, for all practical purposes, rotated through aconstant distance during every operating cycle. Thus, even though thestroke of the screwdriver may be changed, the feeding drum may berotated through an optimum and constant distance at all times so as todrop an adequate number of screws 26 onto the track 53 and yet withoutrotating through an excessive distance and unduly agitating and perhapsdamaging the screws.

Still another machine is shown in FIGS. 20 to 23 and, in this instance,the support 36 is mounted pivotally on the base 37 for horizontalmovement about two horizontally spaced upright axes so that thescrewdriver 30 can be swung to a plurality of positions over theworkpiece 27 in order to drive screws 26 in a series of horizontallyspaced holes 270 formed in the workpiece. To mount the support 36pivotally on the base 37, a post 200 (FIG. 20) upstands from the baseand swingably supports a horizontally extending arm 201. The latter, inturn, is connected pivotally to the support 36 by a pair of verticallyspaced and vertically extending pivot pins 203. Accordingly, thescrewdriver 30 and the support 36 may be swung universally in ahorizontal sense to enable selective positioning of the screwdriverabove each of the holes 27a in the workpiece 27.

In accordance with another aspect of the invention, a simplified finder204 coacts with a unique workpiece-holding fixture 205 to enable precisepositioning of the screwdriver 30 above the holes 27a in an extremelyeasy and simple manner and without requiring the machine operator tomove the finder except as an incident to normal movement of thescrewdriver. As shown in FIGS. 20 to 22, the fixture 205 is anchored tothe base 37 and includes a lower template 206 spaced upwardly from thebase and supporting upright posts 207 upon which the workpiece 27 isadapted to be held during driving of the screws 26. A verticallyextending opening 209 is formed through the template 206, and theupright side walls 210 of the opening are formed with open-sidedrecesses 211 each underlying and corresponding positionally to one ofthe holes 270 in the workpiece. An upright passage 213 extends throughthe inner side wall 210 and establishes communication between theopening 209 and the outside of the fixture.

The finder 204 is bolted rigidly to the underside of the support 36 andcomprises a horizontal arm extending outwardly to a position beneath thescrewdriver 30. An upwardly projecting locator pin 214 is carried on theouter end of the finder and is centered beneath the screwdriver. Toenable precise centering of the pin 214 beneath the screwdriver, the pinis fitted loosely within a hole 215 (FIG. 23) in the outer end of thefinder and is clamped therein by three angularly spaced and radiallyextending set screws 216 threaded into the finder. Thus, by adjustingthe set screws, the pin 214 may be shifted radially within the hole 215until the axis of the pin is in exact vertical alinement with the axisof the screwdriver.

When setting up the machine for use, the operator simply swings thesupport 36 horizontally to move the locator pin 214 horizontally throughthe passage 213 in the template 206 and into the opening 209 therein.Thereafter, the support is simply swung between each cycle to move thepin 214 successively into each of the recesses 211 and, as an incidentto seating in each recess, the pin automatically locates and holds thescrewdriver 30 above the hole 27a overlying the recess so that the screw26 will be driven into the hole when the screwdriver is actuated.Accordingly, it will be apparent that, between each cycle, the operatorneed not first move the finder 204 and the locator pin 214 beforeswinging the screwdriver 30 to a new position. Instead, the locator pinmoves within the opening 209 automatically as an incident to swingingthe screwdriver above the next hole 27a and then lodges in one of therecesses 21] to locate the screwdriver. The pin need be removed from theopening 209 only when the fixture is changed or when service is to beperformed on the machine.

I claim as my invention:

1. An automatic asembly machine having a support, a rotatable feedingwheel on said support for delivering randomly oriented fasteners to anelongated track mounted on the support, a rotatable clearing wheelmounted on said support above said track for sweeping improperlyoriented fasteners ofi' of said track, and a power-reciprocated toolmounted on said support and movable through up and down strokes toreceive properly oriented fasteners transferred from said track and toassemble the fasteners to workpieces, the improvement in said machinecomprising, a rotatable member mounted on said support and turnable backand forth in timed relation to up and down reciprocation of said tool,first and second endless belt drives connecting said rotatable member tosaid feeding wheel and said clearing wheel, respectively, and first andsecond one-way clutches associated with said first and second drives,respectively, and operable to rotate said feeding wheel when said memberis turned in one direction and to rotate said clearing wheel when saidmember is turned in the opposite direction while leaving each wheel idleduring rotation of the other wheel.

2. An automatic assembly machine as defined in claim 1 in which saidclutches include input elements connected to and coaxial with oppositeends of said rotatable member, each clutch further including an outputelement coaxial with said rotatable member and connected to the belt ofthe respective drive.

3. An automatic assembly machine as defined in claim 1 in which saidsupport is disposed on one side of said clearing wheel, the outerperiphery of said clearing wheel being form ed with a plurality ofangularly spaced flutes for sweeping improperly oriented fasteners fromsaid track, said flutes being inclined relative to the axis of saidwheel and in a direction to sweep said improperly oriented fastenerslaterally of said track and toward said support.

4. An automatic assembly machine as defined in claim 2 further includinga transfer device mounted on said support for delivering fasteners fromsaid track to said tool, mechanism for shifiing said transfer deviceoutwardly and in wardly between said track and said tool, and meansoperably connected between said mechanism and said rotatable member forturning the latter in one direction when said transfer device is shiftedoutwardly and in the opposite direction when said transfer device isshifted inwardly.

5. An automatic assembly machine as defined in claim 4 in which saidmechanism moves said transfer device outwardly from said track to saidtool at a comparatively slow rate and moves the transfer device inwardlyfrom said tool to said track at a faster rate, said first clutch beingconnected to rotate said feeding wheel when said rotatable member isturned in one direction and at a comparatively slow rate as saidtransfer device is moved outwardly, and said second clutch beingconnected to rotate said clearing wheel when said rotatable member isturned in the opposite direction and at a faster rate as said transferdevice is moved inwardly.

6. An automatic assembly machine as defined in claim 2 further includinga toothed rack connected to and movable up and down with said tool, apinion rotatably mounted on said support and meshing with said rack, andmeans connecting said pinion to said rotatable member to turn the latterin response to rotation of said pinion.

7. An automatic assembly machine as defined in claim 6 in which thedownstroke of said tool occurs at a slower rate than the upstroke, saidfirst clutch being connected to rotate said feeding wheel when saidmember is rotated in one direction and at a comparatively slow rateduring the downstroke of said tool, and said second clutch beingconnected to rotate said clearing wheel at a faster rate when saidmember is rotated in the opposite direction during the upstroke of saidtool.

8. An automatic assembly machine having a support, a rotatable feedingwheel on said support for delivering randomly oriented fasteners to anelongated track mounted on the support, a rotatable clearing wheelmounted on said support above said track for sweeping improperlyoriented fasteners off of said track, and a power-reciprocated toolmounted on said support and movable through up and down strokes toreceive properly oriented fasteners transferred from said track and toassemble the fasteners to workpieces, the improvement in said machinecomprising, a rotatable member mounted on said support and tumable backand forth in timed relation to up and down reciprocation of said tool,drive means connecting said member to said wheels and including firstand second endless elements for rotating the feeding wheel and theclearing wheel, respectively, and one-way clutch means associated withsaid drive means and operable first to turn said wheels and then toleave said wheels idle as said member rotates back and forth.

9. An automatic assembly machine comprising a support, a power rotateddriver mounted on said support for reciprocation through upward anddownward strokes and operable to engage and drive a fastener during saiddownward stroke, a transfer mechanism movable inwardly and outwardlybetween a loading station and a delivery station and operable first topick up a fastener at said loading station thereafter to move outwardlyto said delivery station to locate the fastener in the downward path ofsaid driver, said transfer mechanism comprising a slide guided on saidsupport for inward and outward movement, a pair of opposed fastenerholder jaws, connectors mounting said jaws on said slide to moveinwardly and outwardly with the latter between said loading and deliverystations and mounting the jaws pivotally on the slide to swing through alimited range between open and closed positions, and actuator meansconnected to said jaws and operable when the jaws are in each station tofirst swing the jaws about said connectors until the jaws stop uponreaching one of said positions, said actuator means being responsive tothe force created by stopping of the jaws and thereafter acting throughsaid connectors to move said slide on said support so as to move thejaws from one station to the other.

10. An automatic assembly machine as defined in claim 9 furtherincluding means carried on said slide and engageable with the jaws tostop swinging of the jaws when the latter reach said open positions,said jaws being stopped upon reaching said closed positions by virtue ofengagement of the jaws with the fastener.

ll. An automatic assembly machine as defined in claim 9 furtherincluding a spring resiliently pressing said slide against said supportto retard movement of the slide on the support during swinging of saidjaws between said open and closed positions.

12. An automatic assembly machine as defined in claim ll in which saidslide comprises a pair of opposed blocks each bearing against saidsupport, said spring being sandwiched between said blocks and urging thelatter away from one another and into pressing engagement with saidsupport.

l3. An automatic assembly machine as defined in claim 9 furtherincluding a pair of links each connected at one end to one of said jawsto pivot about an axis offset from the pivot axis of the jaw, a rodspanning and connected pivotally to the other ends of said links, andsaid actuator means being connected to said rod and being operable toshift said links to first swing said jaws between said positions and,with continued shifting of the links, to move said jaws between saidstations.

14. An automatic assembly machine comprising a support, a carriagemounted for up and down reciprocation on said sup port and carrying apower rotated driver for driving a fastener on the downward stroke ofsaid carriage, a transfer mechanism mounted on said support for inwardand outward movement between a loading station and a delivery station,said transfer mechanism picking up a fastener at said loading stationand thereafter moving outwardly to said delivery station to locate thefastener in the downward path of said driver, a first fluid operatedactuator connected between said support and said carriage forreciprocating the latter upwardly and downwardly, a second fluidoperated actuator connected between said support and said transfermechanism for moving the latter inwardly and outwardly, and coactingmeans movable with said carriage and said transfer mechanism andengageable with one another to prevent said second actuator from movingsaid transfer mechanism outwardly to said delivery station until saidcarriage has been retracted upwardly through a predetermined distance bysaid first actuator.

l5. An automatic assembly machine as defined in claim 14 including meansfor controlling the energization of said actuators and operable toenergize the first actuator in a direction tending to shift saidcarriage upwardly and to simultaneously energize the second actuator ina direction tending to move said transfer mechanism outwardly, saidcoacting means engaging one another and limiting outward movement ofsaid transfer mechanism by said second actuator during the initialperiod of energization thereof.

16. An automatic assembly machine as defined in claim 15 in which saidcoacting means comprise a downwardly and outwardly inclined cam surfaceon said carriage, and a follower movable with said transfer mechanismand positioned to ride outwardly along said cam surface to enableprogressive outward movement of said transfer mechanism as said carriageis shifted progressively upwardly from a predetermined elevation.

17. An automatic assembly machine comprising a support, an uprightsleeve mounted on said support for up and down reciprocation, and apower rotated driver disposed within said sleeve to reciprocate with thelatter through upward and downward strokes and operable during saiddownward stroke to engage and assemble a threaded fastener to aworkpiece, the improvement in said machine comprising, a tubular chucktelescoped into said sleeve and over said driver for holding thefastener beneath the driver during said downward stroke, said chuckbeing mounted to slide up and down relative to the sleeve and the driverbetween raised and lowered positions, a spring mounted within saidsleeve and urging said chuck downwardly toward said lowered position, areleasable latch mounted on said sleeve and engageable with said chuckto hold the latter in said raised position against the bias of saidspring, and means for delivering fasteners one at a time to a positionbeneath said chuck and operable as an incident to such delivery torelease said latch to enable said chuck to slide to said loweredposition and to telescope over the delivered fastener.

18. An automatic assembly machine as defined in claim 17 in which saidmeans comprise a transfer device movable inwardly and outwardly betweenloading and delivery stations, said transfer device picking up afastener at said loading station and delivering the fastener to aposition beneath the chuck at said delivery station, and means forshifting said transfer device outwardly to said delivery station duringthe upward stroke of said driver and for returning the transfer deviceinwardly toward said loading station prior to the next downward strokeof the driver.

19. An automatic assembly machine as defined in claim 17 including anopening in one wall of said sleeve, a downwardly facing edge on saidchuck and registering with said opening when said chuck is in saidraised position, said latch being mounted pivotally on the outer side ofsaid sleeve and being swingable within said opening between a latchedposition in engagement with said edge and a released position spacedoutwardly from said edge, and a spring connected between said sleeve andsaid latch and urging the latter to swing toward said latched position.

20. An automatic assembly machine as defined in claim 19 in whichdownward movement of said chuck with said sleeve is stopped by saidworkpiece prior to the completion of the downward stroke of said driverthereby to cause the chuck to move upwardly relative to the sleeve assaid downward stroke is continued, said latch snapping automatically tosaid latched position and lodging beneath said edge after upwardmovement of said chuck through a predetermined distance relative to saidsleeve,

21. An automatic assembly machine as defined in claim 17 in which thelower end portion of said chuck is formed by at least two opposedsections cantilevered near their upper ends to swing toward and awayfrom one another, means urging said sections away from one another tokeep the chuck open for telescopically receiving a fastener, and matingcam surfaces on said sections and said sleeve engageable with oneanother as an incident to movement of said chuck to said loweredposition and operable in response to such engagement to swing saidsections toward one another into gripping embracement with the fastener.

22. An automatic assembly machine comprising a support, a power rotateddriver mounted on said support for up and down movement, a firstactuator for reciprocating said driver through upward and downwardstrokes, a chuck telescoped over said driver and mounted to moveupwardly and downwardly with the driver and also to move verticallyrelative to the driver between raised and lowered positions, said chuckbeing disposed in said lowered position and holding a fastener beneathsaid driver when the latter is at the top of said upward stroke prior tothe start of an operating cycle, said chuck moving upwardly relative tosaid driver and shifting to said raised position as the fastener isdriven by said driver during said downward stroke, a latch for holdingsaid chuck in said raised position during subsequent movement of saiddriver through said upward stroke, a transfer device movable inwardlyand outwardly on said support between loading and delivery stations,said transfer device picking up a fastener at said loading station anddelivering the fastener to a position beneath said chuck at saiddelivery station, a second actuator for moving said transfer devicebetween said stations and operable to move the transfer device outwardlyto said delivery station when said driver reaches the top of said upwardstroke with said chuck disposed in said raised position, means on saidtransfer device for releasing said latch as the transfer device reachessaid delivery station thereby to enable said chuck to move downwardly tosaid lowered position and pick up the fastener from said transferdevice, and means controlling said second actuator and effecting inwardmovement of said transfer device to said loading station after thefastener has been picked up by said chuck and before operation of saidfirst actuator to begin another cycle and initiate the next downwardstroke of said driver.

23. An automatic assembly machine as defined in claim 22 in which saidtransfer device comprises a slide guided on said support for inward andoutward movement, a pair of opposed fastener holder jaws, connectorsmounting said jaws on said slide to move inwardly and outwardly with thelatter between said loading and delivery stations and mounting the jawspivotally on the slide to swing through a limited range between open andclosed positions, and means connecting said second actuator to said jawsand operable in response to operation of said second actuator when thejaws are in each station to first swing the jaws about said connectorsuntil the jaws stop upon reaching one of the positions and beingresponsive to the force created by stopping of the jaws to thereafteract through said connectors and move said slide on said support so as tomove the jaws from one station to the other.

24. An automatic assembly machine as defined in claim 22 furtherincluding coacting means movable with said driver and said transferdevice and engageable with one another to prevent said second actuatorfrom moving said transfer device outwardly to said delivery stationuntil said driver has been retracted upwardly through a predetermineddistance by said first actuator.

25. An automatic assembly machine as defined in claim 22 furtherincluding a track on said support for delivering fasteners to saidloading station, a rotatable feeding wheel for delivering randomlyoriented fasteners to said track, a rotata ble clearing wheel forsweeping improperly oriented fasteners off of said track, a rotatablemember mounted on said support, means connecting said second actuator tosaid rotatable member to turn the latter back and forth when said secondac tuator is operated to shift said transfer device inwardly andoutwardly, first and second endless belt drives connecting saidrotatable member to said feeding wheel and said clearing wheel,respectively, and first and second one-way clutches associated with saidfirst and second drives, respectively, and operable to rotate saidfeeding wheel when said member is turned in one direction and to rotatesaid clearing wheel when said member is turned in the opposite directionwhile leaving each wheel idle during rotation of the other wheel.

26. An automatic assembly machine as defined in claim 22 furtherincluding a base, said support being mounted pivotally on said base forhorizontal movement about at least two horizontally spaced upright axes,a fixture on said base for holding a workpiece beneath said driver, saidfixture including an opening having upright side walls formed withopen-sided recesses each corresponding positionally to a work point onthe workpiece, a passage extending through one of said side walls andestablishing communication between said opening and the outer side ofsaid fixture, a finder mounted on said support for horizontal movementtherewith, and a vertically extending locator pin carried on said finderand centered beneath said driver, said locator pin being movablehorizontally through said passage and into said opening as an incidentto moving said support horizontally and being adapted to seat in saidrecesses to locate said driver above the work points on said workpiece.

27. An automatic assembly machine comprising a base, a fixture on saidbase for holding a workpiece, said fixture including an opening havingupright side walls formed with open-sided recesses each correspondingpositionally to a work point on the workpiece, a passage extendingthrough one of said side walls and establishing communication betweensaid opening and the outer side of said fixture, an articulated supportmounted pivotally on said base for horizontal movement about at leasttwo horizontally spaced upright axes, a power rotated driver mounted onsaid support for up and down reciprocation, a finder mounted on saidsupport for horizontal movement therewith, and a vertically extendinglocator pin carried on said finder and centered beneath said driver,said locator pin being movable horizontally through said passage and.into said opening as an incident to moving said support horizontally andbeing adapted to seat in said recesses to locate said driver above thework points on said workpiece,

28. An automatic assembly machine as defined in claim 27 in which saidfinder is anchored rigidly to said support and is fixed against verticalmovement relative to said support during operation of said machine.

29. An automatic assembly machine as defined in claim 27 in which saidlocator pin is fitted loosely within a vertically extending hole in saidfinder, and a series of angularly spaced screws extending radially intosaid hole with their inner ends in clamping engagement with said pin,said screws being adjustable radially to enable precise centering ofsaid pin beneath said driver.

30. An automatically fed fastener driving device comprising a supportmember, and a power rotated driver mounted on said support member andoperable to engage and turn a threaded fastener, the improvement in saiddevice comprising, a sleeve telescoped over said driver for locating thefastener relative to the driver, said sleeve being mounted on saidsupport member to slide back and forth relative to the driver between anadvanced position in which one end of the sleeve projects apredetermined distance beyond the working end of the driver and aretracted position in which said one end of the sleeve projects a lesserdistance beyond the working end of the driver, a spring acting betweensaid support member and said sleeve and urging said sleeve toward saidadvanced position, a releasable latch mounted on said support member andengageable with said sleeve to hold the sleeve in said retractedposition against the bias of said spring, and means for deliveringfasteners one at a time to a location beyond said one end of said sleevewhen the sleeve is in said retracted position and operable as anincident to such delivery to release the latch to

1. An automatic assembly machine having a support, a rotatable feedingwheel on said support for delivering randomly oriented fasteners to anelongated track mounted on the support, a rotatable clearing wheelmouNted on said support above said track for sweeping improperlyoriented fasteners off of said track, and a power-reciprocated toolmounted on said support and movable through up and down strokes toreceive properly oriented fasteners transferred from said track and toassemble the fasteners to workpieces, the improvement in said machinecomprising, a rotatable member mounted on said support and turnable backand forth in timed relation to up and down reciprocation of said tool,first and second endless belt drives connecting said rotatable member tosaid feeding wheel and said clearing wheel, respectively, and first andsecond one-way clutches associated with said first and second drives,respectively, and operable to rotate said feeding wheel when said memberis turned in one direction and to rotate said clearing wheel when saidmember is turned in the opposite direction while leaving each wheel idleduring rotation of the other wheel.
 2. An automatic assembly machine asdefined in claim 1 in which said clutches include input elementsconnected to and coaxial with opposite ends of said rotatable member,each clutch further including an output element coaxial with saidrotatable member and connected to the belt of the respective drive. 3.An automatic assembly machine as defined in claim 1 in which saidsupport is disposed on one side of said clearing wheel, the outerperiphery of said clearing wheel being formed with a plurality ofangularly spaced flutes for sweeping improperly oriented fasteners fromsaid track, said flutes being inclined relative to the axis of saidwheel and in a direction to sweep said improperly oriented fastenerslaterally of said track and toward said support.
 4. An automaticassembly machine as defined in claim 2 further including a transferdevice mounted on said support for delivering fasteners from said trackto said tool, mechanism for shifting said transfer device outwardly andinwardly between said track and said tool, and means operably connectedbetween said mechanism and said rotatable member for turning the latterin one direction when said transfer device is shifted outwardly and inthe opposite direction when said transfer device is shifted inwardly. 5.An automatic assembly machine as defined in claim 4 in which saidmechanism moves said transfer device outwardly from said track to saidtool at a comparatively slow rate and moves the transfer device inwardlyfrom said tool to said track at a faster rate, said first clutch beingconnected to rotate said feeding wheel when said rotatable member isturned in one direction and at a comparatively slow rate as saidtransfer device is moved outwardly, and said second clutch beingconnected to rotate said clearing wheel when said rotatable member isturned in the opposite direction and at a faster rate as said transferdevice is moved inwardly.
 6. An automatic assembly machine as defined inclaim 2 further including a toothed rack connected to and movable up anddown with said tool, a pinion rotatably mounted on said support andmeshing with said rack, and means connecting said pinion to saidrotatable member to turn the latter in response to rotation of saidpinion.
 7. An automatic assembly machine as defined in claim 6 in whichthe downstroke of said tool occurs at a slower rate than the upstroke,said first clutch being connected to rotate said feeding wheel when saidmember is rotated in one direction and at a comparatively slow rateduring the downstroke of said tool, and said second clutch beingconnected to rotate said clearing wheel at a faster rate when saidmember is rotated in the opposite direction during the upstroke of saidtool.
 8. An automatic assembly machine having a support, a rotatablefeeding wheel on said support for delivering randomly oriented fastenersto an elongated track mounted on the support, a rotatable clearing wheelmounted on said support above said track for sweeping improperlyoriented fasteners off of said track, and a power-reciprocated toolmounted on said support and movable through up and down strokes toreceive properly oriented fasteners transferred from said track and toassemble the fasteners to workpieces, the improvement in said machinecomprising, a rotatable member mounted on said support and turnable backand forth in timed relation to up and down reciprocation of said tool,drive means connecting said member to said wheels and including firstand second endless elements for rotating the feeding wheel and theclearing wheel, respectively, and one-way clutch means associated withsaid drive means and operable first to turn said wheels and then toleave said wheels idle as said member rotates back and forth.
 9. Anautomatic assembly machine comprising a support, a power rotated drivermounted on said support for reciprocation through upward and downwardstrokes and operable to engage and drive a fastener during said downwardstroke, a transfer mechanism movable inwardly and outwardly between aloading station and a delivery station and operable first to pick up afastener at said loading station thereafter to move outwardly to saiddelivery station to locate the fastener in the downward path of saiddriver, said transfer mechanism comprising a slide guided on saidsupport for inward and outward movement, a pair of opposed fastenerholder jaws, connectors mounting said jaws on said slide to moveinwardly and outwardly with the latter between said loading and deliverystations and mounting the jaws pivotally on the slide to swing through alimited range between open and closed positions, and actuator meansconnected to said jaws and operable when the jaws are in each station tofirst swing the jaws about said connectors until the jaws stop uponreaching one of said positions, said actuator means being responsive tothe force created by stopping of the jaws and thereafter acting throughsaid connectors to move said slide on said support so as to move thejaws from one station to the other.
 10. An automatic assembly machine asdefined in claim 9 further including means carried on said slide andengageable with the jaws to stop swinging of the jaws when the latterreach said open positions, said jaws being stopped upon reaching saidclosed positions by virtue of engagement of the jaws with the fastener.11. An automatic assembly machine as defined in claim 9 furtherincluding a spring resiliently pressing said slide against said supportto retard movement of the slide on the support during swinging of saidjaws between said open and closed positions.
 12. An automatic assemblymachine as defined in claim 11 in which said slide comprises a pair ofopposed blocks each bearing against said support, said spring beingsandwiched between said blocks and urging the latter away from oneanother and into pressing engagement with said support.
 13. An automaticassembly machine as defined in claim 9 further including a pair of linkseach connected at one end to one of said jaws to pivot about an axisoffset from the pivot axis of the jaw, a rod spanning and connectedpivotally to the other ends of said links, and said actuator means beingconnected to said rod and being operable to shift said links to firstswing said jaws between said positions and, with continued shifting ofthe links, to move said jaws between said stations.
 14. An automaticassembly machine comprising a support, a carriage mounted for up anddown reciprocation on said support and carrying a power rotated driverfor driving a fastener on the downward stroke of said carriage, atransfer mechanism mounted on said support for inward and outwardmovement between a loading station and a delivery station, said transfermechanism picking up a fastener at said loading station and thereaftermoving outwardly to said delivery station to locate the fastener in thedownward path of said driver, a first fluid operated actuator connectedbetween said support and said carriage for reciprocating the latterupwardly and downwardly, a second fLuid operated actuator connectedbetween said support and said transfer mechanism for moving the latterinwardly and outwardly, and coacting means movable with said carriageand said transfer mechanism and engageable with one another to preventsaid second actuator from moving said transfer mechanism outwardly tosaid delivery station until said carriage has been retracted upwardlythrough a predetermined distance by said first actuator.
 15. Anautomatic assembly machine as defined in claim 14 including means forcontrolling the energization of said actuators and operable to energizethe first actuator in a direction tending to shift said carriageupwardly and to simultaneously energize the second actuator in adirection tending to move said transfer mechanism outwardly, saidcoacting means engaging one another and limiting outward movement ofsaid transfer mechanism by said second actuator during the initialperiod of energization thereof.
 16. An automatic assembly machine asdefined in claim 15 in which said coacting means comprise a downwardlyand outwardly inclined cam surface on said carriage, and a followermovable with said transfer mechanism and positioned to ride outwardlyalong said cam surface to enable progressive outward movement of saidtransfer mechanism as said carriage is shifted progressively upwardlyfrom a predetermined elevation.
 17. An automatic assembly machinecomprising a support, an upright sleeve mounted on said support for upand down reciprocation, and a power rotated driver disposed within saidsleeve to reciprocate with the latter through upward and downwardstrokes and operable during said downward stroke to engage and assemblea threaded fastener to a workpiece, the improvement in said machinecomprising, a tubular chuck telescoped into said sleeve and over saiddriver for holding the fastener beneath the driver during said downwardstroke, said chuck being mounted to slide up and down relative to thesleeve and the driver between raised and lowered positions, a springmounted within said sleeve and urging said chuck downwardly toward saidlowered position, a releasable latch mounted on said sleeve andengageable with said chuck to hold the latter in said raised positionagainst the bias of said spring, and means for delivering fasteners oneat a time to a position beneath said chuck and operable as an incidentto such delivery to release said latch to enable said chuck to slide tosaid lowered position and to telescope over the delivered fastener. 18.An automatic assembly machine as defined in claim 17 in which said meanscomprise a transfer device movable inwardly and outwardly betweenloading and delivery stations, said transfer device picking up afastener at said loading station and delivering the fastener to aposition beneath the chuck at said delivery station, and means forshifting said transfer device outwardly to said delivery station duringthe upward stroke of said driver and for returning the transfer deviceinwardly toward said loading station prior to the next downward strokeof the driver.
 19. An automatic assembly machine as defined in claim 17including an opening in one wall of said sleeve, a downwardly facingedge on said chuck and registering with said opening when said chuck isin said raised position, said latch being mounted pivotally on the outerside of said sleeve and being swingable within said opening between alatched position in engagement with said edge and a released positionspaced outwardly from said edge, and a spring connected between saidsleeve and said latch and urging the latter to swing toward said latchedposition.
 20. An automatic assembly machine as defined in claim 19 inwhich downward movement of said chuck with said sleeve is stopped bysaid workpiece prior to the completion of the downward stroke of saiddriver thereby to cause the chuck to move upwardly relative to thesleeve as said downward stroke is continued, said latch snappingautomatically to said latched position anD lodging beneath said edgeafter upward movement of said chuck through a predetermined distancerelative to said sleeve.
 21. An automatic assembly machine as defined inclaim 17 in which the lower end portion of said chuck is formed by atleast two opposed sections cantilevered near their upper ends to swingtoward and away from one another, means urging said sections away fromone another to keep the chuck open for telescopically receiving afastener, and mating cam surfaces on said sections and said sleeveengageable with one another as an incident to movement of said chuck tosaid lowered position and operable in response to such engagement toswing said sections toward one another into gripping embracement withthe fastener.
 22. An automatic assembly machine comprising a support, apower rotated driver mounted on said support for up and down movement, afirst actuator for reciprocating said driver through upward and downwardstrokes, a chuck telescoped over said driver and mounted to moveupwardly and downwardly with the driver and also to move verticallyrelative to the driver between raised and lowered positions, said chuckbeing disposed in said lowered position and holding a fastener beneathsaid driver when the latter is at the top of said upward stroke prior tothe start of an operating cycle, said chuck moving upwardly relative tosaid driver and shifting to said raised position as the fastener isdriven by said driver during said downward stroke, a latch for holdingsaid chuck in said raised position during subsequent movement of saiddriver through said upward stroke, a transfer device movable inwardlyand outwardly on said support between loading and delivery stations,said transfer device picking up a fastener at said loading station anddelivering the fastener to a position beneath said chuck at saiddelivery station, a second actuator for moving said transfer devicebetween said stations and operable to move the transfer device outwardlyto said delivery station when said driver reaches the top of said upwardstroke with said chuck disposed in said raised position, means on saidtransfer device for releasing said latch as the transfer device reachessaid delivery station thereby to enable said chuck to move downwardly tosaid lowered position and pick up the fastener from said transferdevice, and means controlling said second actuator and effecting inwardmovement of said transfer device to said loading station after thefastener has been picked up by said chuck and before operation of saidfirst actuator to begin another cycle and initiate the next downwardstroke of said driver.
 23. An automatic assembly machine as defined inclaim 22 in which said transfer device comprises a slide guided on saidsupport for inward and outward movement, a pair of opposed fastenerholder jaws, connectors mounting said jaws on said slide to moveinwardly and outwardly with the latter between said loading and deliverystations and mounting the jaws pivotally on the slide to swing through alimited range between open and closed positions, and means connectingsaid second actuator to said jaws and operable in response to operationof said second actuator when the jaws are in each station to first swingthe jaws about said connectors until the jaws stop upon reaching one ofthe positions and being responsive to the force created by stopping ofthe jaws to thereafter act through said connectors and move said slideon said support so as to move the jaws from one station to the other.24. An automatic assembly machine as defined in claim 22 furtherincluding coacting means movable with said driver and said transferdevice and engageable with one another to prevent said second actuatorfrom moving said transfer device outwardly to said delivery stationuntil said driver has been retracted upwardly through a predetermineddistance by said first actuator.
 25. An automatic assembly machine asdefined in claim 22 further including a track on said support fordelivering Fasteners to said loading station, a rotatable feeding wheelfor delivering randomly oriented fasteners to said track, a rotatableclearing wheel for sweeping improperly oriented fasteners off of saidtrack, a rotatable member mounted on said support, means connecting saidsecond actuator to said rotatable member to turn the latter back andforth when said second actuator is operated to shift said transferdevice inwardly and outwardly, first and second endless belt drivesconnecting said rotatable member to said feeding wheel and said clearingwheel, respectively, and first and second one-way clutches associatedwith said first and second drives, respectively, and operable to rotatesaid feeding wheel when said member is turned in one direction and torotate said clearing wheel when said member is turned in the oppositedirection while leaving each wheel idle during rotation of the otherwheel.
 26. An automatic assembly machine as defined in claim 22 furtherincluding a base, said support being mounted pivotally on said base forhorizontal movement about at least two horizontally spaced upright axes,a fixture on said base for holding a workpiece beneath said driver, saidfixture including an opening having upright side walls formed withopen-sided recesses each corresponding positionally to a work point onthe workpiece, a passage extending through one of said side walls andestablishing communication between said opening and the outer side ofsaid fixture, a finder mounted on said support for horizontal movementtherewith, and a vertically extending locator pin carried on said finderand centered beneath said driver, said locator pin being movablehorizontally through said passage and into said opening as an incidentto moving said support horizontally and being adapted to seat in saidrecesses to locate said driver above the work points on said workpiece.27. An automatic assembly machine comprising a base, a fixture on saidbase for holding a workpiece, said fixture including an opening havingupright side walls formed with open-sided recesses each correspondingpositionally to a work point on the workpiece, a passage extendingthrough one of said side walls and establishing communication betweensaid opening and the outer side of said fixture, an articulated supportmounted pivotally on said base for horizontal movement about at leasttwo horizontally spaced upright axes, a power rotated driver mounted onsaid support for up and down reciprocation, a finder mounted on saidsupport for horizontal movement therewith, and a vertically extendinglocator pin carried on said finder and centered beneath said driver,said locator pin being movable horizontally through said passage andinto said opening as an incident to moving said support horizontally andbeing adapted to seat in said recesses to locate said driver above thework points on said workpiece.
 28. An automatic assembly machine asdefined in claim 27 in which said finder is anchored rigidly to saidsupport and is fixed against vertical movement relative to said supportduring operation of said machine.
 29. An automatic assembly machine asdefined in claim 27 in which said locator pin is fitted loosely within avertically extending hole in said finder, and a series of angularlyspaced screws extending radially into said hole with their inner ends inclamping engagement with said pin, said screws being adjustable radiallyto enable precise centering of said pin beneath said driver.
 30. Anautomatically fed fastener driving device comprising a support member,and a power rotated driver mounted on said support member and operableto engage and turn a threaded fastener, the improvement in said devicecomprising, a sleeve telescoped over said driver for locating thefastener relative to the driver, said sleeve being mounted on saidsupport member to slide back and forth relative to the driver between anadvanced position in which one end of the sleeve projects apredetermined distance beyond the working enD of the driver and aretracted position in which said one end of the sleeve projects a lesserdistance beyond the working end of the driver, a spring acting betweensaid support member and said sleeve and urging said sleeve toward saidadvanced position, a releasable latch mounted on said support member andengageable with said sleeve to hold the sleeve in said retractedposition against the bias of said spring, and means for deliveringfasteners one at a time to a location beyond said one end of said sleevewhen the sleeve is in said retracted position and operable as anincident to such delivery to release the latch to enable the sleeve toslide to said advanced position and to engage and control the deliveredfastener.